1. Field of the Invention
The present invention relates to a liquid ejecting device which ejects liquid as a liquid droplet. This invention is particularly effective when applied to an inkjet recording device (inkjet printer).
2. Description of Related Art
An inkjet recording device forms an image on a recording medium by ejecting a liquid (e.g., ink), in the form of liquid droplets, from an ejecting head (recording head) onto the recording medium (e.g., a sheet).
In such an inkjet recording device, if the liquid droplet is ejected irregularly from the ejecting head (nozzle) because the nozzle for ejecting the liquid droplet (ink) is clogged or the like, then a desired image is not formed on the recording medium. Accordingly, it is desirable to periodically check the ejecting head to detect an ejection failure. One example of how to periodically check the ejecting head to detect an ejection failure is to eject a liquid droplet from the ejection head into/onto an ejection failure detecting unit.
In an invention disclosed in Japanese Unexamined Patent Application Publication No. 9-24621, a pair of electrodes are provided in an ejection failure detecting unit, so that when a liquid droplet is ejected to the ejection failure detecting unit, the liquid droplet causes a short circuit between the pair of electrodes. In the invention disclosed in this publication, it is detected whether or not the liquid droplet is ejected irregularly from an ejecting head (ejection failure of the ejecting head), by determining whether or not electric current flows between the pair of electrodes.
Since liquid such as ink generally has a low conductivity, there is only a small difference between the value of a current flowing between the pair of electrodes when they are in the short-circuited state (i.e., the liquid droplet passes between the electrodes), and the value of a current flowing between the pair of electrodes when they are not in the short-circuited state (i.e., no liquid droplet passes between the electrodes).
Owing to this, it is difficult to accurately detect an ejection failure of the ejecting head with the invention disclosed in the above publication because the determination as to whether or not the electric current flows between the pair of electrodes is not reliable.